Electrical stimulation of the brain has been used to treat any number of neurological disorders including, for example, pain and movement disorders. Electrical leads having many electrodes are implanted in the brain such that one or more cathodal electrodes and one or more anodal electrodes are in optimal locations to produce benefits or to minimize undesirable side effects. An implantable pulse generator (IPG) generates signals to deliver electrical stimulation to the brain tissue via the electrodes. These electrodes or electrodes in other leads, may be also used to record electrical signals that, once adequately processed and analyzed using implantable or portable devices, may be used to monitor the state of the tissue or organ and to also deliver a therapy when this state is approaching abnormalcy. Additionally or alternatively, sets of inputs catheters carrying drugs may be selectively connected to sets of output catheters for drug delivery to surrounding tissue.
Depending on the disorder, sensing and or therapy systems may utilize a large number of electrodes or catheters to monitor and treat the disorder. Accordingly, the treating physician may configure the system with a spatial configuration of cathodes and anodes or of catheters that is best suited for any particular disorder or patient. If required, the treating physician may later optimize the electrode or catheter spatial configuration by selecting different electrodes or catheters from those originally chosen. Also, leads/electrodes or catheters may shift or migrate (in reference to the intended monitoring or therapy target) after being implanted, the chosen electrodes or catheters may “break,” or the intended target site may change over time. To either improve the therapeutic benefits or to replace malfunctioning or off-target electrodes or catheters in prior-art implanted medical devices often requires a major surgical procedure.
Therefore, it is desirable to: a) implant more sensing and/or therapy elements than those actually used (i.e., those which sense electrical signals and/or through which currents or drugs are actually delivered to tissue) so that, by switching certain elements OFF and others ON, electrical currents or drugs continue to be delivered to the intended target or to a new one located within the spatial domain/reach of the sensing and/or therapy elements; and b) accomplish these tasks without further surgery.
Therefore, there exists a need in the art for implantable interfaces for electrical monitoring and/or stimulation and/or for drug delivery having a plurality/surplus of electrodes or catheters that may be selectively chosen and coupled to monitor tissue electrical signals and deliver electrical stimulation or drugs to desired neural tissue, without exceeding or violating size constraints for implantability and/or without requiring additional surgeries.